; ********************** ; ** ** ; ** SERIAL I/O INIT ** ; ** ** ; ********************** ; SIO initialization subroutine SIOINT: lda #%00111100 sta PACTL ; turn off motor lda #%00111100 sta PBCTL ; raise not command line lda #3 sta SSKCTL ; get POKEY out of initialize mode sta SOUNDR ; init poke address for quiet I/O sta SKCTL rts ; *********************** ; ** ** ; ** SIO MAIN ROUTINE ** ; ** ** ; *********************** E971: tsx stx STACKP ; save stack pointer lda #1 sta CRITIC lda DDEVIC cmp #$60 bne @1 ; branch if not cassette jmp CASENT ; otherwise jump to cassette enter ; all devices except cassette are intelligent @1: lda #0 sta CASFLG ; init cassette flag to no cassette lda #1 ; set number of device retries sta DRETRY @2: lda #13 ; set number of command frame retries sta CRETRY ; send a command frame @3: lda #$28 ; set baud rate to 19200 sta $D204 lda #0 sta $D206 clc ; set up command buffer lda DDEVIC adc DUNIT adc #$FF ; subtract 1 sta CDEVIC ; set bus ID number lda DCOMND ; set bus command sta CCOMND lda DAUX1 ; store command frame aux bytes 1 and 2 sta CAUX1 lda DAUX2 sta CAUX2 ; done setting up command buffer clc ; set buffer pointer to cmd frame buf lda #$3A sta BUFRLO ; and buffer end address adc #4 sta BFENLO lda #2 sta BUFRHI sta BFENHI ; done setting up buffer pointer lda #%00110100 ; lower not command line sta PBCTL jsr SENDIN ; send command frame to a smart device lda ERRFLG bne @4 ; branch if an error received tya bne @5 ; branch if ACK received @4: dec CRETRY ; NACK or TIME OUT occured bpl @3 ; so branch if any retries left jmp @10 ; otherwise, jump to return section @5: lda DSTATS ; new stuff... bpl @6 ; send a data frame to a peripheral lda #13 ; set number of retries sta CRETRY jsr LDPNTR ; load buffer pointer with DCB info jsr SENDIN ; send data frame to smart device beq @10 ; branch if bad ; wait for complete signal from peripheral @6: jsr STTMOT ; set device time out values in Y,X lda #0 sta ERRFLG ; clear error flag jsr WAITER ; set up timer and wait beq @8 ; branch if time out ; device did not time out bit DSTATS bvs @7 ; branch if more data follows lda ERRFLG bne @10 ; branch if an error occured beq EA2A ; otherwise return ; receive a data frame from peripheral @7: jsr LDPNTR ; load buffer pointer with DCB info jsr RECEIV ; go receive a data frame @8: lda ERRFLG beq @9 ; branch if no error preceeded data lda TSTAT ; get temp status sta STATUS ; store in real status @9: lda STATUS cmp #1 beq EA2A ; branch if completely successful @10: dec DRETRY bmi EA2A ; branch if out of device retries jmp @2 ; otherwise, one more time EA2A: jsr SENDDS ; disable POKEY interrupts lda #0 sta CRITIC ldy STATUS ; return status in Y sty DSTATS ; and the DCB status word rts ; wait subroutine ; waits for COMPLETE or ACK ; returns Y=$FF if successfull, Y=$00 if not WAIT: lda #0 sta ERRFLG ; clear error flag clc ; load buffer pointer with address lda #$3E ; of temporary RAM cell sta BUFRLO adc #1 sta BFENLO ; also set buffer end +1 address lda #2 sta BUFRHI sta BFENHI ; done loading pointer lda #$FF sta NOCKSM ; set no checksum follows data flag jsr RECEIV ; go receive a byte ldy #$FF ; assume success lda STATUS cmp #1 bne @2 ; branch if it did not work ok lda TEMP ; make sure the byte successfully rec'd cmp #'A' ; was actually an ACK or COMPLETE beq @4 cmp #'C' beq @4 cmp #'E' ; branch if device did not send back bne @1 lda #144 sta STATUS ; set device error status bne @2 @1: lda #139 ; otherwise set NACK status sta STATUS @2: lda STATUS cmp #138 beq @3 ; branch if time out lda #$FF sta ERRFLG ; set some error flag bne @4 ; return with out setting Y = 0 @3: ldy #0 @4: lda STATUS sta TSTAT rts ; return ; send subroutine ; sends a buffer of bytes out over the serial bus SEND: lda #1 ; assume success sta STATUS jsr SENDEN ; enable sending ldy #0 sty CHKSUM ; clear check sum sty CHKSNT ; checksum sent flag sty XMTDON ; transmission done flag lda (BUFRLO),Y ; put first byte from buffer .if (OS_REVISION<=2) sta SEROUT ; into the serial output register sta CHKSUM ; put it in checksum .else sta CHKSUM ; put it in checksum sta SEROUT ; into the serial output register .endif @1: lda BRKKEY bne @2 jmp BROKE ; jump if break key pressed @2: lda XMTDON ; loop until transmission done beq @1 jsr SENDDS ; disable sending rts ; return ; output data needed interrupt service routine ISRODN: tya pha ; save Y reg on stack inc BUFRLO ; increment buffer pointer bne @1 inc BUFRHI @1: lda BUFRLO ; check if past end buffer cmp BFENLO lda BUFRHI ; high part sbc BFENHI bcc @4 ; branch if not pas end of buffer lda CHKSNT bne @2 lda CHKSUM sta SEROUT ; send check sum lda #$FF sta CHKSNT ; set checksum sent flag bne @3 @2: lda POKMSK ; enable transmit done interrupt ora #%00001000 sta POKMSK sta IRQEN @3: pla tay ; restore Y reg pla ; return from interrupt rti @4: ldy #0 lda (BUFRLO),Y ; put next byte from buffer sta SEROUT ; into the serial output register clc adc CHKSUM ; add it to checksum adc #0 sta CHKSUM jmp @3 ; go return ; transmit done interrupt service routine ISRTD: lda CHKSNT beq @1 ; branch if checksum not yet sent sta XMTDON ; otherwise set transmission done flag lda POKMSK ; disable transmit done interrupt and #%11110111 sta POKMSK sta IRQEN @1: pla ; return from interrupt rti RECEIV: lda #0 ldy CASFLG ; branch if cassette bne @1 sta CHKSUM ; clear checksum @1: sta BUFRFL ; buffer full flag sta RECVDN ; receive done flag lda #1 sta STATUS ; set good status for default case jsr RECVEN ; do receive enable lda #%00111100 ; command frame hi command sta PBCTL ; store in PIA @2: lda BRKKEY bne @3 jmp BROKE ; jump if break key pressed @3: lda TIMFLG ; no, beq TOUT ; if timeout, go set error status lda RECVDN beq @2 ; done? rts TOUT: lda #138 ; yes, sta STATUS ; set timeout status rts .if (OS_REVISION=0) .res 9,0 jmp $C28B .res 20,0 .endif ISRSIR: tya pha ; save Y reg on stack lda SKSTAT sta SKRES ; reset status register bmi @1 ; branch if no framing error ldy #140 sty STATUS ; set frame error status @1: and #%00100000 bne @2 ; branch if no overrun error ldy #142 sty STATUS ; set overrun error status @2: lda BUFRFL beq @5 ; branch if buffer was not yet filled lda SERIN ; this input byte is the checksum cmp CHKSUM beq @3 ; branch if checksums match ldy #143 sty STATUS ; set checksum error status @3: lda #$FF sta RECVDN ; set receive done flag @4: pla tay ; restore Y reg pla ; return from interrupt rti .if (OS_REVISION=0) .res 3,0 jmp $E74E .res 26,0 .endif @5: lda SERIN ldy #0 sta (BUFRLO),Y ; store input register into buffer clc ; add it to checksum adc CHKSUM adc #0 sta CHKSUM inc BUFRLO ; increment buffer pointer bne @6 inc BUFRHI @6: lda BUFRLO cmp BFENLO lda BUFRHI sbc BFENHI bcc @4 ; branch if new bufadr is in buffer L lda NOCKSM beq @7 ; branch if a checksum will follow data lda #0 sta NOCKSM ; clear no checksum flag beq @3 ; go return and set receive done flag @7: lda #$FF sta BUFRFL ; set buffer full flag bne @4 ; go return ; load buffer pointer subroutine ; load DCB buffer pointer with DCB buffer information LDPNTR: clc lda DBUFLO sta BUFRLO adc DBYTLO sta BFENLO ; also set buffer end + 1 address lda DBUFHI sta BUFRHI adc DBYTHI sta BFENHI rts ; return ; cassette handling code CASENT: lda DSTATS bpl @3 ; branch if input from cassette lda #<1484 ; set baud rate to 600 sta AUDF3 lda #>1484 sta AUDF4 jsr SENDEN ; turn on POKEY mark tone ldx PALNTS ldy NTSCPAL+4,X ; load short write interrecord gap time lda DAUX2 bmi @1 ; branch if short gap is desired ldy NTSCPAL,X @1: ldx #0 ; set write IRG time jsr SETVBX lda #%00110100 sta PACTL ; turn on motor @2: lda TIMFLG ; loop until done bne @2 jsr LDPNTR ; load buffer pointer with DCB info jsr SEND ; send a buffer jmp @6 ; go return ; receive a record @3: lda #$FF sta CASFLG ; set cassette flag ldx PALNTS ldy NTSCPAL+6,X ; load short read interrecord gap time lda DAUX2 bmi @4 ; branch if short gap is desired ldy NTSCPAL+2,X @4: ldx #0 jsr SETVBX lda #%00110100 sta PACTL ; turn on motor @5: lda TIMFLG ; loop until done bne @5 jsr LDPNTR ; load buffer pointer with DCB info jsr STTMOT ; set device time out in Y,X jsr SETVBX jsr BEGIN ; set initial baud rate jsr RECEIV ; go receive a block @6: lda DAUX2 bmi @7 ; branch if doing short IRG's lda #%00111100 sta PACTL ; turn off motor @7: jmp EA2A JTIMER: lda #0 sta TIMFLG ; set time out flag rts ; send enable subroutine SENDEN: lda #%00000111 ; mask off prev serial bus control bits and SSKCTL ora #%00100000 ; set transmit mode ldy DDEVIC cpy #$60 bne @1 ; branch if not cassette ora #%00001000 ; set the FSK output bit ldy #7 ; set FSK tome frequencies sty AUDF2 ldy #5 sty AUDF1 @1: sta SSKCTL ; store new value to system mask sta SKCTL ; store to actual register lda #%11000111 ; mask off prev serial bus intr bits and POKMSK ora #%00010000 ; enable output data needed interrupt jmp EC56 ; continue in receive enable subroutine ; receive enable subroutine RECVEN: lda #%00000111 ; mask off prev serial bus control bits and SSKCTL ora #%00010000 ; set receive mode asynchronous sta SSKCTL ; store new value to system mask sta SKCTL ; store to actual register sta SKRES ; reset serial port/keyboard status reg lda #%11000111 ; mask off prev serial bus intr bits and POKMSK ora #%00100000 ; enable receive interrupt EC56: sta POKMSK ; store new value to system mask sta IRQEN ; store to actual register lda #%00101000 ; clock CH@3 with 1@79 MHz sta AUDCTL ; clock CH@4 with CH@3 ldx #6 ; set pure tones, no volume lda #%10101000 ldy SOUNDR ; test quiet I/O flag bne @1 ; NE is normal (noisy) lda #%10100000 @1: sta AUDC1,X dex dex bpl @1 lda #%10100000 sta AUDC3 ; turn off sound on channel 3 ldy DDEVIC cpy #$60 beq @2 ; branch if cassette is desired sta AUDC1 ; otherwise turn off channels 1 and 2 sta AUDC2 @2: rts ; return SENDDS: nop ; ?huh? lda #%11000111 ; mask off serial bus interrupts and POKMSK sta POKMSK ; store new value to system mask sta IRQEN ; store to actual register ldx #6 lda #0 @1: sta AUDC1,X dex dex bpl @1 ; turn off audio volume rts ; return ; set device time-out values in Y,X subroutine STTMOT: lda DTIMLO ; get device time out in 1 second incr ror ; put 6 hi bits in X, lo 2 bits in Y ror tay ; temp save and #%00111111 ; mask off hi 2 bits tax ; this is hi byte of time out tya ror and #%11000000 ; mask off all but 2 hi bits tay ; this is lo byte of time out rts ; these are called INTTBL in the OS source, but are not used! .word ISRSIR ; serial input ready .word ISRODN ; output data needed .word ISRTD ; transmission done ; send a data frame to an intelligent peripheral subroutine SENDIN: ldx #1 ; wait a short time... @1: ldy #$FF @2: dey bne @2 dex bne @1 jsr SEND ; go send the data frame ldy #2 ; set ack time out ldx #0 WAITER: jsr SETVBX jsr WAIT ; wait for ack tya ; if Y=0, a TIME OUT or NACK occured rts ; return ; compute value for POKEY freq regs for the baud rate as ; measured by an interval of the 'VCOUNT' timer. COMPUT: sta TIMER2 sty TIMER2+1 ; save final timer value jsr ADJUST ; adjust VCOUNT value sta TIMER2 ; save adjusted value lda TIMER1 jsr ADJUST ; adjust sta TIMER1 ; save adjusted TIMER1 value lda TIMER2 sec sbc TIMER1 sta TEMP1 ; find VCOUNT difference lda TIMER2+1 sec sbc TIMER1+1 tay ; find VBLANK count difference ldx PALNTS lda #0 sec sbc NTSCPAL+8,X @1: clc adc NTSCPAL+8,X ; accumulate multiplication dey bpl @1 ; done? clc adc TEMP1 ; total VCOUNT difference tay ; save accum lsr lsr lsr asl sec sbc #22 ; adjust table index tax ; div interval by 4 to get table index tya ; restore accum and #%00000111 tay ; pull off 3 lo bits of interval lda #$F5 ; -11 @2: clc adc #11 ; accumulate interpolation constant dey bpl @2 ; interp constant computation done? ldy #0 sec sbc #7 ; adjust interpolation constant bpl @3 dey @3: clc adc TPFV,X ; add constant to lo byte table value sta CBAUDL tya adc TPFV+1,X ; add carry to hi byte table value sta CBAUDH rts ADJUST: cmp #$7C bmi @1 ; larger than '7C' ? sec ; yes sbc #$7C rts @1: clc ldx PALNTS adc NTSCPAL+10,X rts ; initial baud rate measurement -- used to set the ; baud rate at the start of a record ; it is assumed that the first two bytes of every record are 'AA' hex BEGIN: lda BRKKEY bne @1 jmp BROKE ; jump if break key pressed @1: sei lda TIMFLG bne @2 ; branch if not timed out beq @4 ; branch if time out @2: lda SKSTAT and #%00010000 ; read serial port bne BEGIN ; start bit? sta SAVIO ; save ser. data in ldx VCOUNT ; read vertical line counter ldy RTCLOK+2 ; read lo byte of VBLANK counter stx TIMER1 sty TIMER1+1 ; save initial timer value ldx #1 ; set mode flag stx TEMP3 ldy #10 ; set bit counter for 10 bits @3: lda BRKKEY beq BROKE ; branch if break key pressed lda TIMFLG bne @5 ; branch if not timed out @4: cli jmp TOUT ; branch if time out @5: lda SKSTAT and #%00010000 ; read serial port cmp SAVIO ; data in changed yet? beq @3 sta SAVIO ; yes, save ser. data in dey ; decr. bit counter bne @3 ; done? dec TEMP3 ; yes, bmi @6 ; done with both modes? lda VCOUNT ldy RTCLOK+2 ; read timer lo & hi bytes jsr COMPUT ; no, compute baud rate ldy #9 ; set bit counter for 9 bits bne @3 @6: lda CBAUDL sta AUDF3 lda CBAUDH sta AUDF4 ; set POKEY freq regs for baud rate lda #0 sta SKCTL lda SSKCTL sta SKCTL ; init POKEY serial port lda #%01010101 sta (BUFRLO),Y ; store '$55' as first rcv. buffer iny sta (BUFRLO),Y lda #%10101010 sta CHKSUM ; store checksum for 2 bytes of '$AA' clc lda BUFRLO adc #2 sta BUFRLO lda BUFRHI adc #0 sta BUFRHI ; incr. buffer pointer by 1 cli rts BROKE: jsr SENDDS ; break key was pressed, so prepare lda #%00111100 ; to return sta PACTL ; turn off motor lda #%00111100 sta PBCTL ; raise not command line lda #128 sta STATUS ; store break abort status code ldx STACKP txs ; restore stack pointer dec BRKKEY ; set break key flag to nonzero cli ; allow IRQ's jmp EA2A ; go return SETVBX: lda #JTIMER sta CDTMA1+1 lda #1 ; set for timer 1 sei ; the SETVBL needs this to cut short jsr SETVBV ; any VBLANKs that occur lda #1 ; set for timer 2 sta TIMFLG ; set flag to not timed out cli rts ; 'VCOUNT' interval timer measurement -- TO -- POKEY freq reg value ; conversion table ; The values stored in the table are 'AUDF+7' ; The followinf formulas were used to determine the table values: ; F OUT = F IN/(2*(AUDF+M)) , where F IN=1@78979 MHz & M=7 ; From this was derived a formula used to compute the table values ; based on a measurement of the period by an interval of the VCOUNT ; timer. ; AUDF+7=(11@365167)*T OUT, where T OUT=# of counts ; (127 usec. resolution) of VCOUNT for 1 character time ; (10 bit times). ; AUDF+7 BAUD RATE VCOUNT INTERVAL ; ------ ----------- ---------------- TPFV: .word $3E8 ; 895 88 .word $443 ; 820 96 .word $49E ; 757 104 .word $4F9 ; 703 112 .word $554 ; 656 120 .word $5AF ; 615 128 .word $60A ; 579 136 .word $665 ; 547 144 .word $6C0 ; 518 152 .word $71A ; 492 160 .word $775 ; 469 168 .word $7D0 ; 447 176 ; PAL / NTSC timing values NTSCPAL: .byte $B4,$96 .byte $78,$64 .byte $0F,$0D .byte $0A,$08 .byte $83,$9C .byte $07,$20